M-Class (W163) 1998-2005: ML 230, ML 320, ML 350, ML 400 CDI, ML 430, ML 500, ML 270 CDI

1999 ml 430 intake vacuum leak repair

Old 08-27-2017, 03:31 PM
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2011 Mercedes Benz ML 550
1999 ml 430 intake vacuum leak repair


Update: Following the below repair all of the below error codes went away. Had to drive about 200 miles to re-establish history and for the "readiness" for smog to be ready. Passed CA smog on the first try. Runs great. Hesitation gone. Fuel mileage up 4 mpg. Power and acceleration is up also. I'm certain that this repair fixed many many vacuum leaks. This truck has 200,235 miles! Still going!!!

I thought I would post a repair of the removal and replacement of an intake manifold on a 1999 MB ML430. This intake has a hose which rots from the inside and is claimed as not replaceable. It is not easily. Error codes were P0703 P0701 Bank 1. Fuel Air mixture error. New intake manifold runs about $900. Shop labor would be about $1,000 minimum. Here is what I did for about $225. Long post.

So I tried to pull off the vacuum hose which goes in the front bottom of the intake manifold. It's down low in the center bottom of the front of the intake. DO NOT DO THIS. THE HOSE GOES UP INTO THE MANIFOLD. THERE IS NO NIPPLE AT THE BOTTOM. This worked. The codes cleared. Truck is running very smooth. Power and acceleration is back to normal. Should pass smog. Check engine light and PO701, PO03 codes cleared. John

Lower intake hose in front bottom of intake manifold broke it off flush. It was rotted. Truck has 200K miles. Here is the fix. This is a modification of a post saw on line from about 2012.
Included are the most significant items related to the repair. Refer to intake manifold removal and replacement well documented in other posts. The focus of this repair is on fixing the lower intake hose and all of the other rotted hoses on the intake manifold causing a Fuel Air mixture error with the above codes.

1. Remove air box and air filter.
2. Remove radiator over flow tank.
3. Remove Intake ducting.
4. Remove air pump. Front and center.
5. Unplug all fuel injector wiring, fuel rail and fuel injectors.
6. Unplug all ignition wiring. Tie wiring harness off to the drivers side.
7. Unplug all sensors on intake manifold.
8. Spray ERG pipe nut 24mm, it will be rusted. Let it pre soak then loosen the nut. Leave on manifold, remove on bench. Clean it well. Or replace it. Mine was 75% clogged.
9. Way back in the rear bottom of the intake is the fuel injection main wiring plug. It plugs in coming from the Psg side towards the drivers side. It has two plastic tabs on the top and bottom. These need to be spread up and down respectively. Gently pull towards the passenger side. They are thin don't break them.
10. Remove intake manifold.

ml 430 v8 prior to disassembly. Grid look is because of the shade above.

Another engine photo before taking apart. Take lots of close ups before disassembly. Especially the vacuum hoses. You will need it later.

Prior to disassembly. I took lots of photos.

This photo helped with the dual vac motor hose reassembly.

Photo of intake manifold after splitting the top off. You can see the butterfly valves which are opened by the two two intake valve motors one for each side. You can see the drivers side valve in the picture just above this one. As you step on the gas, the vacuum opens these secondary valves and allows more air in to mix with the additional fuel. Cleaned up with engine cleaner.

So red hose is 3/8" or 9.5mm High Temp vac hose from Summit Racing pushed up onto the manifold from the bottom. Get the right ID" Prior to this photo, drill out, pick and pull out the old black rubber hose until it is gone. I'm measuring with a coat hanger, and blue tape the distance for the red hose to slide up so I know that it is all the way up prior to filling the void from the top.

My red vacuum hose markers. Note that I used this hose placed up into the manifold with the 1 1/4" mark even with the bottom of the manifold. Turn the hose prior to curing of the high temp aluminum epoxy every 15 min for about 2 hours.

See the "D" shape in the middle pointing up. There are two voids on either side and a hose barb coming off the bottom of it inside of the "blind" chamber. The hose comes up from the bottom.

See the void on either side of the "D" shape in the middle on the far right. The link rod goes right by it. These two voids go all the way to the bottom and through the hole where the vacuum hose comes up. There is a hose barb in the middle inside of this cavity. This area spans the upper and the lower secondary vacuum chambers. Hence the purpose of the butterfly valves. This entire cavity will be sealed closed with high temp 2 part epoxy aluminum putty. Lots of cleaning first.

Now fill with high temp aluminum epoxy putty about the size of a golf ball. The epoxy should be filled all around the "D" mentioned earlier. Be sure to push lots of it down. You need to fill about 1" down. About the size of a golf ball. Be sure the red hose is in. Leave it high and level with the right and left sides of the alum top.

Ok, sand any rough areas flat. Then drill a 1/8" hole on either side of the putty through the 1" of putty. Coat hanger is checking that the hole drilled goes through the epoxy and hanger will touch bottom. We will fill the entire cavity with "The Right Stuff" silicone sealant. One hole for in, one hole to let the air out. Use a 1/8" vaccuum joint fitting in the end of the caulk gun. Press hard against the left hole. It will take about 2 min. to fill before it comes up the right hole.

I drilled the left hole slightly bigger than the right side hole. I think 3/16" to get the calk to flow. Hence, already messy as I had started. And drilled a hole inn the calk tube to insert the vacuum connector bit. Look down a couple of shots for this vacuum connector tube. Stops in the calk gun and has a flange on the tube to prevent it from going in the manifold. Press hard with the calk gun don't let it leak around the top, it has to go inside left hole and out the hole on the right.

Measuring for the cavity depth and marking the hose with tape markers.

Zoom in if you can. The 1/8" vacuum line connector is shoved tight fit into the calk tube tip. Make a tight fit by trimming the calk tube tip just enough to make a tight seal on the vac tube.

Prior to full. I've started filling from the left hole.

Cavity is full as you see The Right Stuff has come up the hole on the right. Very little leaked out of the left hole while filling.

Clean the outside with acetone. then I Smeared The Right Stuff around the bottom red hose and the manifold. Likely not needed.

11. Remove the top bolts from the intake manifold and split the two halves. MB indicates no serviceable parts inside. There are not any. But you need access to fix the vacuum line.
12. Clean all oil and grease off the two halves.
13. Don't get throttle body wet or soaked.
14. Fun begins.

15. Pull the vacuum line out of the hole from the bottom. It will break off. You will not be able to see it. Use a pair of pointed needle nose pliers to pull pick and dig out the vacuum line via the 3/8" hole from the bottom. Use a narrow screw driver and drive out the rotted rubber from the bottom hole all the way through the intake to the inside. There is a space between either side of the nipple which is about 3/8" by 1/2". See 5th photo. This space goes all the way through the manifold. This space represents a rectangular box. It is separated from the upper and lower intake chambers by the last "wall" on the intake drop in which is not removable. Don't even try. It is pressed in. I'll refer to these two slots as "Gaps" hereafter. Plan on 2 hours to dig out the old hose. At the top of the hole is a fat part of the hose about 5/8"x 1/2" in diameter from the factory. The hose then drops down and reduces to the 3/8" hose which you see coming out the bottom of the intake. Remove all of it.
16. Clean the Gap area from the top side where the vacuum line attaches. Use engine de-greaser, Wire brushes, tooth brush. Clean the cavity with pipe cleaners, engine cleaner. Clean the bottom outside where the vacuum hose exits. Clean with de-greaser and Acetone. Were going to seal this later.
17. Sand Gap area until shiny alum. Use a shop vacuum often to vac. up the debris. Clean it again. Clean with Acetone as last step. Blow out everything prior to the next steps with compressed air. Both top and bottom halves. Use good workmanship cleaning up the sealing and epoxy surfaces for excellent adhesion.
18. The Concept: Seal the gaps with Epoxy putty. While also being able to keep the vacuum nipple available for a new high temp vacuum hose. Then we will need to fill this cavity with high temp sealant while having the hose connected. This is to prevent vacuum leak out the bottom of the hose cavity. So a bit tricky. There are also two vacuum chambers. The upper for regular driving. And the lower which is activated by the runner valves and the secondary air pump. It's called a variable vacuum intake. The secondary's provide power at low and high engine demands.
19. Put a 3/16' x 3/8' vacuum hose up into the bottom hole. Call this the "form" hose. Think of a concrete form. This hose will not fit tight on the hose barb. It should slide up 1 1/8" into the manifold. Place a piece of tape on the hose to mark the intersection at the bottom of the manifold where the hose exits. Use duct taps.
this is a critical measurement. Pull out hose. Measure and double check that it is 1 1/8" of hose above your tape marker.
20. Let's get this sealed up. Place the above 3/16"x3/8" marked vacuum hose up into the bottom hole. Make sure it is all the way up to the tape mark. tape it into place so it does not fall out as you will seal the top gaps with epoxy putty.
21. Buy JB Weld High Temp Epoxy Putty. Cut off about 1" of putty off the roll. kneed until a uniform color. Handles 400 degrees. 500 intermittent.
22. Press putty into the Gaps form the top until flush with the 1/4" housing on the upper side. Your basically sealing off the "upper vacuum chamber from the lower chamber. Your also sealing this off from leaking to the outside. Press smooth with your fingers. Don't skimp on the putty used. Not more than a 1" of putty is required.
23. Rotate the Form vacuum hose from the bottom. We will remove this hose after the epoxy has cured. Rotate in another 10-30 minutes. Do not use any wax, oil or other items on the form hose. Just rotate it around to ensure it can be removed the next day.
24. Next day remove hose. Insert new 3.5 MM High Temp vacuum hose. You will have to special order this. It is used for hot rods, racing and engine dress up. It is oil resistant does not rot and handles high heat. 400 degrees. Notice that this hose is slightly larger on the OD than the Form hose. That's good. This hose will fit tight on the hose barb. Cut the end of the Red hose clean and square with a razor blade. Mark the hose 1 1/8" from the end with tape. Make sure this does not come off. I used duct tape as regular tape does not stick to silicone hose.
25. Ok now we have sealed the gaps, we have on a new quality high temp 3.5MM red vacuum hose. This red hose will have a snug but not air tight fit at the bottom hole. Let's make some insurance that this does not leak.
26. Concept: With the red hose installed and taped into place we are going to drill two holes into the new epoxy. One hole with a 3/16" drill bit. On the left side parellel to the left side gap. The second hole on the right side of the gap, with a 1/4" drill bit. Were going to drill through the epoxy down into the air gap. Then were going to inject Permatex The Right Stuff Black into the cavity to fill the area around the hose and the aluminum housing. So essentially were filling the area permanently. We want to ensure that the full cavity is filled. We do not want a vacuum leak at the intersection of the bottom of the silicon hose and the intake housing. Permatex The Right Stuff Black is oil resistant. Don't use grey.
27. This part is tricky. The nozzle of the permatex is too short to reach the 3/16" hole. I use a 1/8" vacuum tube connector. Trim back the Right Stuff a tiny bit at at time until you can insert the vacuum tube into it. You will basically need an additional 1" in length. You will need a tight seal between the Right Stuff and the 3/16" hold. Press down hard on the Right STuff. If the sealant is coming out around the tip...make a better seal. Think of a grease fitting. Follow the direction on the Right Stuff. Insert the tip of the Right Stuff into the smaller 3/16" hole. Depress the trigger. It will take about 2-3 minutes to inject the Right Stuff into the cavity to fill all around the silicone red hose until you see it come UP the right 1/4" hole. Once it comes up you will know it is full. So as the caulk goes in air comes out the 1/4" hole. Once you see the black caulk coming up the 1/4" hole your done.
28. As a 3rd added measure put a nice fat bead of the Right stuff on the bottom outside of the intake manifold where the red hose exits. Let cure.
29. Sealing the top half of the Intake manifold. Remove all of the old factory silicone gasket from the top half of the intake manifold lid. Clean the bottom half also. Clean both surfaces absolutely clean with engine de-greaser. Then clean it again with Acetone.
30. Get out the Right Stuff. Slowly and carefully place a nice fat bead onto the top lid. Don't miss any areas. Make sure it is uniform. There is a 1/8" trough in the top lid. The bottom half is flat. On the top lid be sure to go around each bolt hole. Only the outside perimeter is required to be sealed along with the bolt holes. Place lid onto the bottom half carefully, making perfect alignment. Drop in bolts. I torqued mine to 55 inch pounds. Wipe the edges all around of excess before curing. It sets up fairly quickly.
31. The Right Stuff does not need to tack up. Put it on, torque to specs and put it into service. By the time this is cured and re-installed it will be at least another 5-6 hours by the time you have it re-inistalled in the car.
32. Other Misc. repairs done at this time:
33. Replacde ALL vacuum hoses on the intake at this time. AND at the back of the engine. There are several. Do not leave any to chance. Do them one at a time. Take a lot of good photos before starting this job and during. I referred to many photos I took to get all the vacuum lines back on.
34. Replace all fuel injector rubber O rings.
35. Replace all rubber intake manifold hoses. I'll post a list.
36. Parts list from Pelican Parts. Most are URO parts except as noted.
1. 112-018-09-MBZ. This is the center section of the breather hoses. There are Three of them connected to this. This will likely break, is brittle and broke.. MB OEM
2. 112-108-01-82-M1253 Breather hose from Valve Cover Bottom Section.
3. 112-018-02-09-MBZ Breather hose Connector MB.
4. 112-018-02-82-m1253 Breather hose center Section.
5. 112-018-03-82-m1253 Breather hose top section.
6. 112-018-04-82-m1253 Breather hose valve cover to air intake.
7. 112-141-00-83-MBZ MB OEM Hose. Goes from to intake to vacum box. Mine split, hard, dried out. about 1 1/2" x 3" elbow.
8. 112-141-221-80-m17 EGR Line Gasket to Intake Manifold.
9. 112-238-00-82-M58 Air Pump Check Valve Hose-Check Valve to Check Valve. This is the long hose with 3 openings.
10. 113-141-09-80-mbz Intake manifold gaskets. 2 req. Left or right. OEM MB. Don't risk non MB OEM here. Just my opinion.
11. 13-64-1-286-708-INT Fuel Injector Seal. 2 ea x 8 =16 seals
12. 604-094-13-04-m55 Mahle air filter.
13. Total cost about $175.
14. Permatex The Right Stuff. $26. Worth every penny. Only buy a fresh can. don't try the caulk gun version. Use the pressurized can.
15. Cleaners and solvents $30.

Total time about 16 hours. Cleaning time was +3 significant as this truck has 200K miles on it. This is my father in laws truck. He helped with a lot of clean up of the various parts and pieces. Engine compartment was also cleaned up significantly.

Note that if a vacuum line is hard or brittle just replace it. It makes no sense to do all this work and to band aid a 5-10 hose or part.
Attached Thumbnails 1999 ml 430 intake vacuum leak repair-img_8747.jpg   1999 ml 430 intake vacuum leak repair-img_8800.jpg   1999 ml 430 intake vacuum leak repair-img_8751.jpg   1999 ml 430 intake vacuum leak repair-img_8801.jpg   1999 ml 430 intake vacuum leak repair-img_8745.jpg  

Last edited by johnml550; 03-10-2018 at 12:34 AM. Reason: Add photos, add comment.
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Old 03-10-2018, 12:09 AM
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2011 Mercedes Benz ML 550
Per a user request I have added photos and detail on how this repair was done. Hope this helps another user. The 1999 ML 430 v8 is running super. Replace all rubber hoses. I purchased most all of mine through Pelican Done miss any! I think the two holes drilled were 1/8" not 3/16. The lid is sealed with Permatex The Right stuff. It comes in a pressurized can and will "pump" into the cavity. Don't try anything else as you won't get it through a 1/8" hole. Plus it won't work especially for the lid. Be sure The right Stuff squishes out all sides of the lid. I went around all the inside and outside flanges surfaces, especially the outside and the bolt holes.
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Old 02-18-2019, 05:15 PM
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ML430 SL500 SLK230
John: Thank-you for the write-up. I split the intake manifold as well and reading your post.

29. Sealing the top half of the Intake manifold. Remove all of the old factory silicone gasket from the top half of the intake manifold lid. Clean the bottom half also. Clean both surfaces absolutely clean with engine de-greaser. Then clean it again with Acetone.
30. Get out the Right Stuff. Slowly and carefully place a nice fat bead onto the top lid. Don't miss any areas. Make sure it is uniform. There is a 1/8" trough in the top lid. The bottom half is flat. On the top lid be sure to go around each bolt hole. Only the outside perimeter is required to be sealed along with the bolt holes. Place lid onto the bottom half carefully, making perfect alignment. Drop in bolts. I torqued mine to 55 inch pounds. Wipe the edges all around of excess before curing. It sets up fairly quickly.

So, there is not replacement for the "silicone gasket on the top lid? You have to bead it up with right stuff?

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